An organic EL (Electroluminescence) display device has been known as a typical example of a display device. An organic EL display device has an organic light-emitting element (hereinafter, referred to as a light-emitting element) in each of multiple pixels formed over a substrate. A light-emitting element has a layer containing an organic compound (hereinafter, referred to as an EL layer or an organic layer) between a pair of electrodes and is operated by supplying current between the pair of electrodes. During operation of the light-emitting element, the organic compound is oxidized or reduced to exist in a charged state which further undergoes recombination to generate an excited state. Since such an active species in a charged state or an excited state has higher reactivity than a compound in an electrically neutral state or a ground state thereof, the active species reacts with another organic compound or readily reacts with impurities entering the light-emitting element, such as water and oxygen. Products resulting from these reactions influence the properties of the light-emitting element and cause reduction in efficiency and lifetime of the light-emitting element.
Japanese Patent Application Publication No. 2015-15089 discloses, as a method for suppressing deterioration in such properties, forming a region (shielding region) for blocking impurities between a display region including light-emitting elements and a peripheral region surrounding the display region. The formation of the shielding region effectively prevents impurities from entering particularly from an edge portion of a substrate, which improves reliability of a display device.